Direct wiring a transmitter to receiver or ESC?
08-21-2013, 08:08 AM
#1
Direct wiring a transmitter to receiver or ESC?
First off, I know it is at my own risk and expenses that I will be doing this project. I know this will avoid any warranties but there are no warranties left to avoid and I know the equipment I have can handle the motor's stall and surge current. So please don't rant on how I should not do this...
Anyway, does anyone know if this is even possible? I am working on an electric bike and need to directly wire a signal line over to either the receiver or speed control for it. This will take up much less space and eliminate any glitching.
I currently have a couple 5-10 year old 27mhz radios from traxxas and losi I was hoping to use but could use some information on how best to go about it.
If this fails, I could always program a microprocessor to create the signal from an ADC read. I already did this once making a DC motor driver (aka a very basic brushed ESC). But this takes time and resources that I don't have assess to on a weekly basis.
Any help would be greatly appreciated guys!
-Steven
Anyway, does anyone know if this is even possible? I am working on an electric bike and need to directly wire a signal line over to either the receiver or speed control for it. This will take up much less space and eliminate any glitching.
I currently have a couple 5-10 year old 27mhz radios from traxxas and losi I was hoping to use but could use some information on how best to go about it.
If this fails, I could always program a microprocessor to create the signal from an ADC read. I already did this once making a DC motor driver (aka a very basic brushed ESC). But this takes time and resources that I don't have assess to on a weekly basis.
Any help would be greatly appreciated guys!
-Steven
08-21-2013, 10:14 AM
#2
Are you using a electric bike specific speed controller? If not, I would not suggest using rc grade stuff to power a full size bike. RC stuff, even 1/5 scale stuff is not designed to hand the watts and amps your talking about with a bike. Plus your talking about adding in alot of failure points, with a bike speed controller it does everything you need, all you have to add is some sort of throttle control.
Unless your doing something completely different and then some specifics would greatly help.
Unless your doing something completely different and then some specifics would greatly help.
08-21-2013, 10:29 AM
#3
I will be using a 400a 300v IGBT to power the 2.5hp, 12v brushed motor in place of the FETS on an ESC. So its programed like a rc controller and uses the same signal.
The bike controllers only go up to 1000W from what I have seen. This motor is a 1865W motor. If you assume 60% efficiency for the motor, then that's around 250-260 amps. I know this is way too powerful for your standard bicycle, I will not be using all of it, its just what motor I could find at a price I could afford.
I have the control system working with a huge heat sink and everything. I just need to find a way to direct wire the signal for the throttle on the bike.
The bike controllers only go up to 1000W from what I have seen. This motor is a 1865W motor. If you assume 60% efficiency for the motor, then that's around 250-260 amps. I know this is way too powerful for your standard bicycle, I will not be using all of it, its just what motor I could find at a price I could afford.
I have the control system working with a huge heat sink and everything. I just need to find a way to direct wire the signal for the throttle on the bike.
Last edited by rc_dude; 08-21-2013 at 10:41 AM.
08-21-2013, 11:41 AM
#4
I will be using a 400a 300v IGBT to power the 2.5hp, 12v brushed motor in place of the FETS on an ESC. So its programed like a rc controller and uses the same signal.
The bike controllers only go up to 1000W from what I have seen. This motor is a 1865W motor. If you assume 60% efficiency for the motor, then that's around 250-260 amps. I know this is way too powerful for your standard bicycle, I will not be using all of it, its just what motor I could find at a price I could afford.
I have the control system working with a huge heat sink and everything. I just need to find a way to direct wire the signal for the throttle on the bike.
The bike controllers only go up to 1000W from what I have seen. This motor is a 1865W motor. If you assume 60% efficiency for the motor, then that's around 250-260 amps. I know this is way too powerful for your standard bicycle, I will not be using all of it, its just what motor I could find at a price I could afford.
I have the control system working with a huge heat sink and everything. I just need to find a way to direct wire the signal for the throttle on the bike.
Another thing is the motor you picked up, is it rated for sustained high rpms?
alot of brushed larger motors are not designed for high rpms but high torque and short running times.
I had this really long explanation written out and realized it had nothing to do with what your asking.
PWM with a potmeter as the adjustment.
08-21-2013, 12:49 PM
#5
sounds like a pretty sweet setup, only thing I can suggest is to get a 24v or 36v engine and run in series. What your suggesting is very close to an old school style of speed controller, and with 12v your pulling a ton of amps, tons. There is a reason most electric bikes run on high voltage and less watts.
Another thing is the motor you picked up, is it rated for sustained high rpms?
alot of brushed larger motors are not designed for high rpms but high torque and short running times.
I had this really long explanation written out and realized it had nothing to do with what your asking.
PWM with a potmeter as the adjustment.
Another thing is the motor you picked up, is it rated for sustained high rpms?
alot of brushed larger motors are not designed for high rpms but high torque and short running times.
I had this really long explanation written out and realized it had nothing to do with what your asking.
PWM with a potmeter as the adjustment.
I am not truely sure about the motor, it's mainly for actually getting the project going and using for a year or two until I can get the money to refine everything and make it better.
And yes, I was on a robotics team the past two years and we had to figure out how to signal the servos to move to certain angles to operate a claw for picking up blocks. the interval is 20 microseconds and a duty cycle (or on time) of 1-2 +/- microseconds controlled the angle of the servo, so ESC's should operate off the same interval and they just use the "brain" inside them to calculate how long to actually leave the gate open on the MOSFETs to achieve full forward/stop/full reverse. Of course it's more complicated than that with multiple transistors but the concept is the same.
But does anyone have a clue how/if I could direct wire a transmitter? I just don't know enough about radios yet.
08-21-2013, 01:29 PM
#6
FYI this is just spit balling about what little I now about circuits and electronics in general.
are you asking to wire the TX directly to the RX or TX to the ESC?
have you tried to wire a potmeter across the +V wire to the signal wire?
What you need to figure out is what kind of voltage signal the ESC wants to see from the signal wire. If is something simple like .1v to 5v that would really easy to do. I may be thinking of this incorrectly, you already have a esc that has a PWM built into it, then you just need to control that.
or is the signal wire looking to be grounded? if the esc wants to see 0 ohms for stop and infinit ohms for full speed, then your going to have to do some experimenting with this. You will have to find the curve for what ohms is equal to what speed.
If your talking about the robotics team as in lego mind storm thing then this is completely different. I did that first semester of college and it was nothing compared to circuit designs and programming.
Did you program this ESC your self?
Honestly you shouldn't need to direct wire a transmitter. You need to come up with a self returning throttle type device if you plan to ride this.
are you asking to wire the TX directly to the RX or TX to the ESC?
have you tried to wire a potmeter across the +V wire to the signal wire?
What you need to figure out is what kind of voltage signal the ESC wants to see from the signal wire. If is something simple like .1v to 5v that would really easy to do. I may be thinking of this incorrectly, you already have a esc that has a PWM built into it, then you just need to control that.
or is the signal wire looking to be grounded? if the esc wants to see 0 ohms for stop and infinit ohms for full speed, then your going to have to do some experimenting with this. You will have to find the curve for what ohms is equal to what speed.
If your talking about the robotics team as in lego mind storm thing then this is completely different. I did that first semester of college and it was nothing compared to circuit designs and programming.
Did you program this ESC your self?
Honestly you shouldn't need to direct wire a transmitter. You need to come up with a self returning throttle type device if you plan to ride this.
08-21-2013, 02:07 PM
#7
FYI this is just spit balling about what little I now about circuits and electronics in general.
are you asking to wire the TX directly to the RX or TX to the ESC?
have you tried to wire a potmeter across the +V wire to the signal wire?
What you need to figure out is what kind of voltage signal the ESC wants to see from the signal wire. If is something simple like .1v to 5v that would really easy to do. I may be thinking of this incorrectly, you already have a esc that has a PWM built into it, then you just need to control that.
or is the signal wire looking to be grounded? if the esc wants to see 0 ohms for stop and infinit ohms for full speed, then your going to have to do some experimenting with this. You will have to find the curve for what ohms is equal to what speed.
If your talking about the robotics team as in lego mind storm thing then this is completely different. I did that first semester of college and it was nothing compared to circuit designs and programming.
Did you program this ESC your self?
Honestly you shouldn't need to direct wire a transmitter. You need to come up with a self returning throttle type device if you plan to ride this.
are you asking to wire the TX directly to the RX or TX to the ESC?
have you tried to wire a potmeter across the +V wire to the signal wire?
What you need to figure out is what kind of voltage signal the ESC wants to see from the signal wire. If is something simple like .1v to 5v that would really easy to do. I may be thinking of this incorrectly, you already have a esc that has a PWM built into it, then you just need to control that.
or is the signal wire looking to be grounded? if the esc wants to see 0 ohms for stop and infinit ohms for full speed, then your going to have to do some experimenting with this. You will have to find the curve for what ohms is equal to what speed.
If your talking about the robotics team as in lego mind storm thing then this is completely different. I did that first semester of college and it was nothing compared to circuit designs and programming.
Did you program this ESC your self?
Honestly you shouldn't need to direct wire a transmitter. You need to come up with a self returning throttle type device if you plan to ride this.
Honestly i had never heard of a potmeter before today... going to have to research those some.
I can't remember what the voltage was for the signal right now, but I don't remember it being very picky by any means. I think anything above about 2.5 or 3 worked? I'll have to ask one of the team members.
For the robot, we got 8th place out of 66 teams in the IEEE hardware competition at to south eastern conference in the spring, here is a picture.
I do not know how to program, this is my main problem. I am studying mechanical engineering and was the only ME on the robot team (this is how I learned so much about electrical). But I had to transfer to another school witch is why I am up a creek...
I don't know anyone here yet that can help me. At my old school I was working with an electrical student and professor to design and build a basic-forward only speed control using a pot, microcontroller, and the IGBT. We believe we got all the designs worked out but were never able to build and test the final product and make sure. We fried 2 IGBT's (thankfully it was the schools money) due to gate capacitance building up. I don't have the money to try again out of my own pocket and fail...
Thanks for the help though, i guess this project may just have to wait until next year...
08-21-2013, 02:25 PM
#8
Thats a pretty killer robot. looks like it would be a ton of fun.
The key to getting this to work is, your going to have to figure out what voltage/ohms the input is looking for. Hopefully the Micro chip input was programmed for a linear input. starting pulling up the data sheets for all of your components and find out what they are rated at.
So, im assuming how your circuit works is, the Micro controller is a PWM built into 1 chip and it controls the gates of the IGBT's. and the Pot is for adjusting the frequency of?
If this is correct you should be able to look up the data sheet on the micro controller and you can see what its maximum voltage is for input signal.
How much are we talking about per IGBT here? I found a price of 12 bucks a pop for ones with specs you listed.
wait you said you never heard of a potmeter but you have one on your ESC that you built.
The key to getting this to work is, your going to have to figure out what voltage/ohms the input is looking for. Hopefully the Micro chip input was programmed for a linear input. starting pulling up the data sheets for all of your components and find out what they are rated at.
So, im assuming how your circuit works is, the Micro controller is a PWM built into 1 chip and it controls the gates of the IGBT's. and the Pot is for adjusting the frequency of?
If this is correct you should be able to look up the data sheet on the micro controller and you can see what its maximum voltage is for input signal.
How much are we talking about per IGBT here? I found a price of 12 bucks a pop for ones with specs you listed.
wait you said you never heard of a potmeter but you have one on your ESC that you built.
08-21-2013, 02:51 PM
#9
Thats a pretty killer robot. looks like it would be a ton of fun.
The key to getting this to work is, your going to have to figure out what voltage/ohms the input is looking for. Hopefully the Micro chip input was programmed for a linear input. starting pulling up the data sheets for all of your components and find out what they are rated at.
So, im assuming how your circuit works is, the Micro controller is a PWM built into 1 chip and it controls the gates of the IGBT's. and the Pot is for adjusting the frequency of?
If this is correct you should be able to look up the data sheet on the micro controller and you can see what its maximum voltage is for input signal.
How much are we talking about per IGBT here? I found a price of 12 bucks a pop for ones with specs you listed.
wait you said you never heard of a potmeter but you have one on your ESC that you built.
The key to getting this to work is, your going to have to figure out what voltage/ohms the input is looking for. Hopefully the Micro chip input was programmed for a linear input. starting pulling up the data sheets for all of your components and find out what they are rated at.
So, im assuming how your circuit works is, the Micro controller is a PWM built into 1 chip and it controls the gates of the IGBT's. and the Pot is for adjusting the frequency of?
If this is correct you should be able to look up the data sheet on the micro controller and you can see what its maximum voltage is for input signal.
How much are we talking about per IGBT here? I found a price of 12 bucks a pop for ones with specs you listed.
wait you said you never heard of a potmeter but you have one on your ESC that you built.
I'll have to do a lot of file digging and such this weekend to find the datasheets on them all again. But you are right on the circuit but we also has an optoisolator since the gate needed about 5.5v to run and the controller could only do about 4ish
And the IGBT we picked was was $36 from digikey.com (just looked and they don't even have them anymore) and the freewheeling diod to handle that many amps is another $30, but thankfully those don't fry as easy.
Most of them with those ratings only have the really small tabs to solder wires to and from experience, those wires cannot hold that many amps without unsoldering themselves... The IGBT we got has the tabs to bolt wires to, as in car battery wires.
And i thought you were referring to a potmeter as something other than a potentiometer... oops
Last edited by rc_dude; 08-21-2013 at 04:12 PM.
08-21-2013, 04:12 PM
#10
If the speed control you are using accepts the "normal" positive-going pulse, about 1 to 2 milliseconds long, repeated about every 15 to 20 milliseconds, you don't need the transmitter or receiver, or even a microprocessor or any programming ability. You can easily build a pulse generator from a 555 timer and a few components:
http://www.hvlabs.com/555servo.html
If you don't want to build it, then you can buy it:
http://www3.towerhobbies.com/cgi-bin...?&I=LXVK79&P=7
The IGBT may not have been a good choice for the motor drive for a 12V source. The forward voltage drop will be pretty large, and will waste a bunch of power. But you can always use the heat sink to cook hot dogs while you ride!
http://www.hvlabs.com/555servo.html
If you don't want to build it, then you can buy it:
http://www3.towerhobbies.com/cgi-bin...?&I=LXVK79&P=7
The IGBT may not have been a good choice for the motor drive for a 12V source. The forward voltage drop will be pretty large, and will waste a bunch of power. But you can always use the heat sink to cook hot dogs while you ride!
08-21-2013, 04:18 PM
#11
The robot was very fun! If you find yourself interested and lacking things to do, here is a video of it on youtube.
I'll have to do a lot of file digging and such this weekend to find the datasheets on them all again. But you are right on the circuit but we also has an optoisolator since the gate needed about 5.5v to run and the controller could only do about 4ish
And the IGBT we picked was was $36 from digikey.com (just looked and they don't even have them anymore) and the freewheeling diod to handle that many amps is another $30, but thankfully those don't fry as easy.
Most of them with those ratings only have the really small tabs to solder wires to and from experience, those wires cannot hold that many amps without unsoldering themselves... The IGBT we got has the tabs to bolt wires to, as in car battery wires.
And i thought you were referring to a potmeter as something other than a potentiometer... oops
I'll have to do a lot of file digging and such this weekend to find the datasheets on them all again. But you are right on the circuit but we also has an optoisolator since the gate needed about 5.5v to run and the controller could only do about 4ish
And the IGBT we picked was was $36 from digikey.com (just looked and they don't even have them anymore) and the freewheeling diod to handle that many amps is another $30, but thankfully those don't fry as easy.
Most of them with those ratings only have the really small tabs to solder wires to and from experience, those wires cannot hold that many amps without unsoldering themselves... The IGBT we got has the tabs to bolt wires to, as in car battery wires.
And i thought you were referring to a potmeter as something other than a potentiometer... oops
08-22-2013, 06:44 AM
#12
Frist post: That servo tester is actually pretty cool, never knew they existed, but then again it never crossed my mind.
I also feel like the IGBT was a bad choice, but the professor is oddly the one who recommended them.
Second post: It should be easy...I just don't know anything about programming the microcontroller...
On another note, I stayed up late last night and am eating my time this morning looks up higher voltage motors to use and everything. Found some interesting things I found this motor that I could afford by selling the motor I already have. Then I found these controllers and I wire both of them parallel to one of the pots, maybe bolt a bigger heat sink or fan to the both of them if needed. Or just get one of these controllers should do it. Then maybe I can get help from mom or hurry up to sell my e-maxx roller to buy the batteries.
Anyway, I better get ready and go to my physics 2 lecture. lol
I also feel like the IGBT was a bad choice, but the professor is oddly the one who recommended them.
Second post: It should be easy...I just don't know anything about programming the microcontroller...
On another note, I stayed up late last night and am eating my time this morning looks up higher voltage motors to use and everything. Found some interesting things I found this motor that I could afford by selling the motor I already have. Then I found these controllers and I wire both of them parallel to one of the pots, maybe bolt a bigger heat sink or fan to the both of them if needed. Or just get one of these controllers should do it. Then maybe I can get help from mom or hurry up to sell my e-maxx roller to buy the batteries.
Anyway, I better get ready and go to my physics 2 lecture. lol
08-22-2013, 08:06 AM
#13
After having done some research into electric bikes I would really suggest the Magic Pie hub motor. Its brush less out-runner that is super efficient and comes with a controller.
Only thing you would have to do is get some Life batteries and build the battery pack. I would really suggest getting a motor designed for electric bikes. using one of the old school brushed motors will have tons of torque but would not be designed for sustained running.
Only thing you would have to do is get some Life batteries and build the battery pack. I would really suggest getting a motor designed for electric bikes. using one of the old school brushed motors will have tons of torque but would not be designed for sustained running.
08-22-2013, 09:46 AM
#14
After having done some research into electric bikes I would really suggest the Magic Pie hub motor. Its brush less out-runner that is super efficient and comes with a controller.
Only thing you would have to do is get some Life batteries and build the battery pack. I would really suggest getting a motor designed for electric bikes. using one of the old school brushed motors will have tons of torque but would not be designed for sustained running.
Only thing you would have to do is get some Life batteries and build the battery pack. I would really suggest getting a motor designed for electric bikes. using one of the old school brushed motors will have tons of torque but would not be designed for sustained running.
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